The Weird Connection Between Your Moles And Your Breast Cancer Risk

Here's the deal: This week, two large studies published in the journal PLOS Medicine linked moles to breast cancer. But there's no need to start frantically counting your beauty marks just yet.

The first study, from researchers at Harvard and Indiana University, followed 74,523 women for 24 years, and found that women with 15 or more moles had an 11.4% chance of developing breast cancer, compared to 8.48% for women with no moles. The second, from the French Institute of Health and Medical Research (INSERM), followed 89,902 women for 18 years, and found that women with the highest number of moles had a 13% higher breast cancer risk than women who didn't have any moles.

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Which isn't good news, but also isn't as scary as it sounds. In both studies, the mole-related risk disappeared after researchers adjusted for other elements, like certain hormonal factors or a family history of breast cancer. That means that having moles would only increase a woman's odds for developing breast cancer if she was already at a heightened risk from one of those other factors, says INSERM study co-author Marie-Christine Boutron-Ruault.

And even then, the findings don't mean that moles cause breast cancer. "Something causes cancer when it is directly responsible for, say, the mutation of cells," says Boutron-Ruault. Moles, on the other hand, appear to be a marker for some common genetic or hormonal things that might also have the potential to cause breast cancer.

What's more, the findings are definitely a good thing, say researchers. The mole-breast cancer connection only held true for premenopausal women. And right now, experts know little about what causes breast cancer in this population (versus post-menopausal women), whose cancers tend to get diagnosed later and progress faster. "In premenopausal breast cancer, we have to find markers that could induce a screening, or at least some type of prevention," says Boutron-Ruault.